1. Field of the Invention
The present invention relates to a joint for connecting double pipes, each of which is provided with an outer pipe, an inner pipe supported inside of the outer pipe and connection ribs for connecting the outer pipe and the inner pipe and is integrally formed by extrusion forming or drawing forming, and a brazing method for brazing the joint with the double pipes.
2. Description of the Related Art
Conventional double pipe is provided with an outer pipe for transfer of a first fluid and an inner pipe for transfer of a second fluid. The double pipe is categorized as two types in a viewpoint of production methods thereof. According to a first type, the outer pipe and the inner pipe inserted thereto, which are individually produced, are ironing-formed so that projections formed on an inner surface of the outer pipe are press-welded to an outer surface of the inner pipe, thereby the inner and outer pipes are formed to be a double pipe. According to a second type, the outer pipe, the inner pipe and ribs for connecting the outer pipe and the inner pipe are integrally formed by extrusion forming or drawing forming. The double pipe of the second type is heavily used because of a low production cost thereof.
Japanese Patent No. 2595578 discloses a related art of a joint for a double hosepipe made of rubber.